Antenna device for automotive vehicle

ABSTRACT

The present invention presents an antenna device for an automotive vehicle wherein a first coil is installed horizontally to receive radio signals. Capacitors are connected electrically and in parallel with the first coil. A second coil is connected electrically with the first coil and installed horizontally under the first coil. A third coil is connected electrically between the first coil and the ground and installed horizontally under the first coil. Additionally, a fourth coil is connected electrically between the first coil and the second coil and installed vertically under the first coil. This antenna device, now including the first to the fourth coils and capacitors, is installed in a mirror case for the car.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an antenna device for an automotivevehicle. More particularly, it relates to an antenna device forautomotive vehicle, in which the antenna and accompanying elements areinstalled inside a mirror case for the automotive vehicle, therebyobviating the problem that the antenna is curved by air resistance andincreasing reception sensitivity level of radio signals.

2. Description of the Prior Art

Generally, the car has an audio system for providing the driver withinformation about traffic conditions and comfortable environment.Nowadays, the audio system is installed in a car as a basic part.Drivers can listen to music or news through the car audio system. Theycan avoid boring conditions due to long drives and select the optimaldriving course referring to the traffic news information.

The audio system requires an antenna to receive radio signals. Thedipole antenna is generally installed on the outside of the car anddriven by an electric motor.

In this conventional dipole antenna, however, there are the problemsthat the antenna is curved by air resistance when the car is driving ata high speed and reception sensitivity level of radio signals islowered.

To solve the problems, an antenna installed in the windshield glass ofthe car in the form of the pattern is provided. Because the antenna madeof copper or silver paster is patterned and formed in the windshieldglass, it can not be bent by the wind during the drives.

The antenna formed in the windshield glass has a problem that staticelectricity produced by friction between the wind and windshield glassis acting as electrical noises thereby the quality of the receptionsignal is degraded.

SUMMARY OF THE INVENTION

Therefore the object of the present invention is to provide an antennadevice for an automotive vehicle, in which an antenna and accompanyingelements are installed in a sideview mirror case or a rearview mirrorcase, thereby obviating the problem that the antenna is curved by airresistance when the car is driving.

The another object of the present invention is to provide an antennadevice for an automotive vehicle, in which reception sensitivity levelof radio signals is increased by arranging several antennas in verticaland horizontal direction according to the electomagnetive radio wavesignals.

The above object has been achieved by the present invention, whichprovides an antenna device for an automotive vehicle comprising:

a first coil installed horizontally to receive radio signals, capacitorsconnected with the first coil in electrical parallel,

a second coil connected electrically with the first coil and installedhorizontally under the first coil,

a third coil connected electrically between the first coil and theground and installed horizontally under the first coil, and

a fourth coil connected electrically between the first coil and thesecond coil and installed vertically under the first coil,

and characterizing that from the first to the fourth coils andcapacitors are installed in a mirror case for the automotive vehicle.

Further, according to the present invention, an antenna device for anautomotive vehicle is provided, comprising:

a power source for supplying the electricl power;

an antenna for receiving radio signals by means of a cored coil;

a band pass filter for permitting a certain frequency range component ofthe received signals from the antenna to pass through;

an amplifier for amplifying the filtered signal from the band passfilter;

and characterizing that the antenna, the band pass filter and theamplifier are installed in a mirror case for the automotive vehicle.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other adventages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain in the principles of theinvention.

In the drawings:

FIG. 1 is a circuit diagram of an antenna device for automotive vehicleaccording to the present invention.

FIG. 2 is a partial cross-sectional view where the antenna device isestablished in a rear-view mirror according to the present invention.

FIG. 3 is a block diagram of an antenna device for automotive vehicleaccording to another embodiment of the present invention.

FIG. 4 is a circuit diagram of the antenna device according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

Referring now to FIG. 1 and FIG. 2, there is shown the antenna deviceaccording to the first embodiment of the present invention.

The first coil L1 is installed horizontally inside a rearview mirrorcase M. The capacitors C1 and C2 are respectively connected with thefirst coil L1 in electrical parallel. The second coil L2 is connectedelectrically with the first coil L1 and installed horizontally under thefirst coil L1. The third coil L3 is connected electrically between thefirst coil L1 and the ground and installed horizontally under the firstcoil L1. The fourth coil L4 is connected electrically between the firstcoil L1 and the second coil L2 and installed vertically under the firstcoil L1. The first coil L1, the second coil L2, the third coil L3, thefourth coil L4 and the capacitors C1 and C2 are installed in a mirrorcase M.

All elements inside the mirror case M is fixed on a printed circuitboard and the output terminal of the printed circuit board is connectedto a receiving apparatus such as the audio system via a coaxial cable.

The following description relates to the operation of the antenna deviceaccording to the first embodiment of the present invention.

When the audio system is powered on, the induced currents are producedin the coils L1 to L4 by the radio broadcasting signal and flow throughthe coils L1 to L4. The coil antenna can receive the radio broadcastingsignal inductively whereas the dipole antenna should contact with theradio signal to receive it.

Intensity of the received signal through the-coils L1 to L4 varies inaccordance with the kind of core which is rolled by the coil. In thepresent invention, ferrite, a magnet or a copper pipe can be used as thecore.

The signal received by the coils L1 to L4 is transferred to a receivingapparatus such as the audio system through a coaxial cable, thereby thereceiving apparatus comes into action.

The performance of the antenna device according to the first embodimentof the present invention can be verified by a numerical expression asfollows.

When the antenna is formed of a coil with ferrite bar core which has aradius α, large permeability and turns N, the receiving voltage Voc inAM area is given like the following.

Voc=−jwμ_(e)μ_(o) Nπα ² Hi=−j(2π/λ_(o))μ_(e) Nπα ²Ei

When the length of the ferrite bar core is very large in comparison withthe radius α and permeability is very large over 1, the effectivepermeability μ_(e) is obtained like the following.

μ_(e)=(1/a ²)/(ln(2l/α)−1)

In the case, the radiating resistance Ra of the antenna is as follows.

Ra=320π⁶(γ_(o)/λ_(o))⁴ N ²μ² _(e)

Therefore, when γ_(o) equals 0.5 cm, N equals 100 and (l/α) equals 100,Ra equals 0.0013Ω and Xa is highly capacitive as the impedance of theantenna at 1 MHz.

From above evaluation, it can be found that the antenna device accordingto the present invention is of good performance in comparison with thedipole antenna.

From now on, the following explanation relates to the second embodimentof the present invention.

Referring to FIG. 3 and FIG. 4, there is shown the antenna deviceaccording to the second embodiment of the present invention.

The power source 10 supplies electric energy. As the power source 10, asmall battery cell or a storage battery for the car can be used. Thepower filter 20 is connected to the power source 10 and filters offelectrical noises.

The antenna 30 comprises core 31 and the coil 32 wound on the core 31.Ferrite, a magnet or a copper pipe can be used as the core 31.

The power filter 20 and the antenna 30 are connected to the band passfilter 40. The band pass filter 40 includes the capacitor C41 connectedbetween the output terminal of the power filter 20 and the ground, thecoil L41 connected with the output terminal of the filter 20, thecapacitor C42 connected between the coil L41 and the ground, the coilL42 connected between the output terminal of the antenna 30 and theground, the resistor R41 connected between the out put terminal of theantenna 30 and the ground, the capacitor C43 connected with the outputterminal of the antenna 30, the operational amplifier A41 connected withthe capacitor C43, the capacitor C44 connected with the input terminalof the operational amplifier A41, the capacitor C45 connected to theinput terminal of the operational amplifier A41 the resistor R42connected between the capacitor C45 and the output terminal of theoperational amplifier A41, and the capacitor C46 connected between theoperational amplifier A41 and the ground.

The power filter 20 and the band pass filter 40 are connected to theamplifier 50. The amplifier 50 comprises the capacitor C51 connectedwith the output terminal of the band pass filter 40, the capacitor C52connected with the capacitor C52, the resistor R51 connected with thecapacitor C52, the resistor R52 connected between the capacitor C52 andthe ground, and the operational amplifier A51 connected with thecapacitor C52.

The antenna 30, the band pass filter 40 and the amplifier 50 areinstalled in the mirror case for the automotive vehicle. All elementsinside the mirror case is fixed on a printed circuit board, and theinput and output of the printed circuit board is connected to areceiving appratus like the audio system through a coaxial cable.

The following description relates to the operation of the antenna deviceaccording to the second embodiment of the present invention.

When a power switch of the audio system turns on, the power source 10 iselectrically connected with the power filter 20. The power sourcesupplies the electrical power signal for the power filter 20. The powerfilter 20 eliminates noises from the power signal. Then, the powerfilter 20 applies the filtered power signal to the band pass filter 40and the amplifier 50. When the filtered power signal is applied to theband pass filter 40 and the amplifier 50, they start to work.

In the meantime, the induced currents are produced in the antenna 30 bythe radio broadcasting signal and applied to the band pass filter 40.The antenna 30 can receive the radio broadcasting signal inductivelywhereas the dipole antenna should contact with the radio signal toreceive it. Intensity of the received signal through the antenna 30varies in accordance with the kind of core 31.

The band pass filter 40 permits a certain frequency range component ofthe signals from the antenna 30 to pass through. The amplifier 50amplifies the signal from the band pass filter 40, then applies theamplified signal to the audio sytem.

Because the antenna 30, the band pass filter 40 and the amplifier 50 areinstalled in a mirror case for the car, there is no problem such as thebend due to air resistance during the drives.

As described above, an antenna device where an antenna and accompanyingelements are installed in a sideview mirror case or a rearview mirrorcase is provided. According to the present invention, the antenna devicecan be prevented from curving due to air resistance when the car isdriving, and reception sensitivity of the antenna device can beincreased.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in an antenna device for anautomotive vehicle of the present invention without departing from thescope and sprit of the invention. Thus it is intended that the presentinvention cover the modifications and variations of this inventionprovided they come within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. An antenna device for an automotive vehiclecomprising: a first coil installed horizontally to receive radiosignals; capacitors connected with the first coil in electricalparallel; a second coil connected electrically with the first coil andinstalled horizontally under the first coil; a third coil connectedelectrically between the first coil and a ground and installedhorizontally under the first coil; a fourth coil connected electricallybetween the first coil and the second coil and installed verticallyunder the first coil; cores rolled by the coils respectively; and aprinted circuit board to fix and connect all elements physically andelectrically; wherein said coils, capacitors, cores, and the printedcircuit board are packed in a mirror case for the automotive vehicle. 2.The device as set forth in claim 1, wherein the core is ferrite.
 3. Thedevice as set forth in claim 1, wherein the core is the magnet.
 4. Thedevice as set forth in claim 1, wherein the core is the copper pipe. 5.The device as set forth in claim 1, wherein the mirror is the rearviewmirror.
 6. The device as set forth in claim 1, wherein the mirror is thesideview mirror.
 7. An antenna device for an automotive vehiclecomprising: a power source for supplying the electrical power; anantenna for receiving radio signals by means of a cored coil; a bandpass filter using an operational amplifier for permitting a certainfrequency range component of the received signals from the antenna topass through; an amplifier for amplifying the filtered signal from theband pass filter; and a printed circuit board to fix and connect allelements physically and electrically; wherein the antenna, the band passfilter, the amplifier, and the printed circuit board are installed in amirror case for the automotive vehicle.
 8. The device as set forth inclaim 7, where in the antenna includes a core and the coil wound.
 9. Thedevice as set forth in claim 8, wherein the core is ferrite.
 10. Thedevice as set forth in claim 8, wherein the core is the magnet.
 11. Thedevice as set forth in claim 8, wherein the core is the copper pipe. 12.The device as set forth in claim 7, wherein the mirror is the rearviewmirror.
 13. The device as set forth in claim 7, wherein the mirror isthe sideview mirror.